Yes, that was my main concern about sweating, even more than getting a good workout. I remember in gym I would get SO sick, and I know it was because I couldn't cool down.

I don't know why I have a slow RHR; it MAY be that my heart is naturally fit, but if so it's not because I've been working at it. The heart size thing is interesting; I'll have to look into that. I do know that my blood pressure is also quite low, though still healthy ... at this point, it's about 95/60 most of the time. (It was 120/70 before I started Atkins.)

I think I will try a combo of the advice from both of you. I will try to work at my THR as you suggested, senrides, and I will then see what my "perceived level of exertion is," as alopex suggested, and adjust from there. I'm a little afraid of pushing my heart to the max so early in my workout routine, so I may try that later.